Currently, multicarrier modulation (MCM) techniques may be used to enable transmission of a set of data over multiple narrow band subcarriers simultaneously. With an advanced wideband modulation and coding scheme (MCS), a system such as a communication system with MCM may achieve much higher spectral efficiency in frequency selective channels comparing to those using signal carrier modulation techniques. For example, a family of MCM techniques such as Filter bank multicarrier (FBMC) modulation may be used in a communication system. FBMC may include a prototype filter that may be designed or implemented to achieve a particular property or goal such as minimizing inter-symbol interference (ISI), inter-carrier interference (ICI), stop band energy, and the like. One particular type of FBMC that may be used in a communication system may include Orthogonal Frequency Division Multiplexing (OFDM). OFDM may include a time domain prototype filter that may be a simple rectangular pulse. From a complexity perspective, OFDM may be used over other FBMC techniques, because OFDM may be easier to implement and/or design in a communication system.
Although OFDM may be easier to implement, large sidelobes of the rectangular pulse in OFDM create challenging issues in a typical communication system. For example, the performance of the systems at physical (PHY) layer may be sensitive to frequency offset. In addition, in some communication systems such as those in TV white space and heterogeneous systems or networks with small cells, multiple radio links may coexist in congested spectral bands, but may be loosely controlled or coordinated in resource usage (e.g. in frequency, timing and/or power). In such a network, strong adjacent channel interference may be generated from large out-of-band emission that may be partially contributed from large sidelobes at the baseband. Additionally, in OFDM, a modulated signal may exhibit a large peak-to-average power ratio (PAPR) that may lead to low efficiency power amplifiers (PAs).
To address the foregoing (e.g. improve a PAPR, channel interference, frequency offset, resource usage, and the like), different FBMC techniques including the orthogonal frequency division multiplexing-offset quadrature amplitude modulation (OFDM-OQAM) have been developed. In OFDM-OQAM, subcarriers of the signal overlap each other to achieve a higher spectral efficiency. Real and imaginary parts of the QAM symbols may also be processed separately with 2×symbol rate unlike OFDM. As such, a filter that may be used with OFDM-OQAM may need to be carefully designed to minimize or zero out ISI and ICI while keeping the sidelobes small. Currently, due to complexity, latency and other issues, OFDM-OQAM and the filter that may be used therewith may not be suitable for use in communication systems.